# Signatures of free carriers in Raman spectra of cubic In$_2$O$_3$

## TL;DR

This study investigates how free carriers affect Raman spectra in n-type In$_2$O$_3$, revealing features that can be used to quantify carrier concentration non-invasively.

## Contribution

It demonstrates the use of Raman spectroscopy to detect free carrier effects and Fano resonances in cubic In$_2$O$_3$, providing a contactless method for carrier concentration measurement.

## Key findings

- Identification of broad electronic excitations below 300 cm$^{-1}$
- Observation of Fano resonances in phonon lines
- Potential for non-contact carrier density determination

## Abstract

We discuss the influence of free carriers on the Raman scattering in $n$-type In$_2$O$_3$. For high-quality cubic single crystals, electronic single-particle excitations are revealed as a relatively broad Raman feature in the frequency range below 300~cm$^{-1}$. Furthermore, discrete phonon lines in the same frequency range exhibit asymmetric lineshapes characteristic for Fano resonances. The two observed spectral features contain the potential to be utilized for the quantitative determination of the free carrier concentration in $n$-type In$_2$O$_3$ using Raman spectroscopy as a contactless experimental technique.